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Item Indentation fracture toughness of Aluminium-Graphite composites: influence of nano-particles(Gruppo Italiano Frattura, 2025) Ibrahim, A.; Niyaz Ahamed, M.B.; Ashoka, E.; Rajesh, A.M.; Bharath, P.B.; Doddamani, D.In the field of composite materials, extensive research has been undertaken on aluminum-graphite composites. However, a research gap has been identified regarding the specific influence of nano-sized graphite particles on their fracture toughness. Previous studies have predominantly focused on larger graphite particles or different reinforcement materials, resulting in relatively unexplored effects of nano-graphite particles. This research is deemed critical as it has the potential to generate lightweight, high-strength materials, aligning with the demands of aerospace, automotive, and structural engineering. The primary objective of this study is to investigate how the inclusion of nano-sized graphite particles affects the fracture toughness of aluminum-graphite composites. To achieve this objective, systematic dispersion and incorporation of nano-sized graphite particles into an aluminum matrix will be carried out. Mechanical testing, including fracture toughness assessments, will be conducted to evaluate the performance of the composite materials. Factors such as particle size, distribution, volume fraction, and interfacial bonding will also be characterized within the study. It is anticipated that the presence of nano-sized graphite particles will lead to a significant enhancement of the fracture toughness of the aluminum-graphite nanocomposites. This enhancement is expected to be attributed to crack deflection, tortuosity, altered stress distribution, and increased plastic deformation around cracks. © 2024.Item Tribological performance and 3-D surface characterisation of age-hardened Al2090-based ceramic composites(SAGE Publications Ltd, 2025) Sharath, B.N.; Mahesh, V.; Mahesh, V.; Kattimani, S.; Harursampath, D.This study investigates the synergistic influence of boron nitride (BN) tertiary ceramic additives and age-hardening treatment on the microhardness and wear resistance of Al2090-based hybrid composites, fabricated using the stir casting method. X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM) studies are carried out to assess the phases present, microstructure, and surface properties, respectively. The metallurgical investigations confirm a relatively superior uniformity in the distribution of particles and the ageing of precipitation at 150°C, vis-à-vis the other temperatures explored in this study. The experimental examinations conducted as per ASTM (E8 and G99) standards revealed a significant improvement in both the hardness and the primary tribological properties, when micron-sized boron carbide, graphite, and boron nitride were used as reinforcements. Age-hardened samples, especially the hybrid composite HS-2 with 5 wt.% each of boron carbide, graphite, and boron nitride, demonstrated an enhanced hardness of 25.23% and lower surface roughness (44.3 nm) compared to Al2090 (AS), due to the presence of load-bearing ceramic reinforcements. Increasing the applied load led to higher wear rates and coefficients of friction for Al2090. However, heat-treated hybrid metal matrix composites (HMMCs) exhibited a contrary behaviour, suggesting enhanced durability. The investigation highlighted the better wear resistance of heat-treated and near-optimally reinforced HMMCs, indicating their potential candidature for wear-resistant aerospace applications. © IMechE 2025.Item On enhancing the high-temperature wear behaviour of Al2090-based hybrid composites using tertiary ceramic particles(SAGE Publications Ltd, 2025) Sharath, B.N.; Mahesh, V.; Mahesh, V.; Kattimani, S.; Harursampath, D.This study explores the impact of reinforcing an Al2090 matrix with silicon nitride (Si3N4) as a tertiary ceramic alongside boron carbide (B4C) and graphite (Gr) to improve wear resistance at elevated temperatures. Hybrid composite samples were produced using the stir-casting technique. Experimental results show that incorporating Si3N4increased hardness by 35.7%, while wear resistance improved by 43.7% with a combined reinforcement of B4C, Gr, and Si3N4at 18 wt.%. Scanning electron microscopy (SEM) revealed the formation of a mechanically mixed layer (MML) composed of B4C, Gr, and Si3N4, which acted as an effective insulating barrier, protecting the sample surface from the steel disc. A noteworthy 69% of wear resistance improvement was accomplished at 300 °C for the composite with 9 wt.% B4C, 6 wt.% Gr, and 3 wt.% Si3N4. Atomic force microscopy (AFM) analysis further indicated enhanced surface properties for this composition. These findings highlight the potential of this hybrid composite for high-temperature aerospace applications, such as in engines, heat shields, and structural components. © IMechE 2024